No one else might be using your account, but you would not have logged out of Facebook, leaving the session active.

If you headed home from office, without logging out of Facebook or Gmail, you can do so from anywhere using the ‘remote log out’ feature.In Facebook, click on the tiny gear sign on the top right of the page, go to ‘account settings’ and then to ‘security’ on the left pane. Under ‘security settings’, click on ‘active sessions’.

No one else might be using your account, but you would not have logged out of Facebook, leaving the session active. Anyone can gain access to your account in such circumstances. To remote log out, click on ‘end activity’.

In Gmail, at the bottom right side of the page, you will see details of your latest email access. If someone else is simultaneously using your account, you will see a notification there.

Click on the ‘Details’ link below it. A new window opens, with a notification on whether the account is simultaneously open elsewhere. Like in the case of FB, you might not have logged out of the account, leaving it active. If so, you will see an option to ‘log out of all sessions’. It also shows you the details of your previous 10 accesses to the account.

As Facebook prepares to update investors on its performance in the first three months of the year, with analysts forecasting revenues up 36% on last year, studies suggest that its expansion in the US, UK and other major European countries has peaked.

In the last month, the world’s largest social network has lost 6million US visitors, a 4% fall, according to analysis firm SocialBakers. In the UK, 1.4million fewer users checked in last month, a fall of 4.5%. The declines are sustained. In the last six months, Facebook has lost nearly 9million monthly visitors in the US and 2m in the UK.

Users are also switching off in Canada, Spain, France, Germany and Japan, where Facebook has some of its biggest followings. A spokeswoman for Facebook declined to comment.

“The problem is that, in the US and UK, most people who want to sign up for Facebook have already done it,” said new media specialist Ian Maude at Enders Analysis. “There is a boredom factor where people like to try something new. Is Facebook going to go the way of Myspace? The risk is relatively small, but that is not to say it isn’t there.”